1. Field of the Invention
The present invention relates to a flat display panel, being a flat display device that displays characters, graphics and images using light emission produced by ionized gas, and particularly to an electrode structure which produces a glow discharge.
2. Description of the Related Art
Conventional flat display panels use plasma display panels. This type of display panel is disclosed in, for example, Japanese Patent Laid-open Publication No. Hei 2-90192(Mar. 29, 1990) and Japanese Utility Model Application Laid-open Publication No. Hei 3-94751(Sep. 26, 1991). In that structure, two substrates, each having a plurality of linear electrodes formed thereon are arranged in parallel so as to face each other. The linear electrodes formed on one substrate and the linear electrodes formed on the other substrate are disposed in a matrix form. Gas discharges occur at intersections between the linear electrodes on one substrate and the linear electrodes on the other substrate.
In such a conventional flat display panel, voltages are applied to the ends of the linear electrodes lead out of the side end surfaces of the plate. The electrodes arranged on the front plate are formed of a transparent electrode material such as ITO through which the emitted light produced by gas discharge can pass. However, The transparent electrode material has a considerably large resistance value because of its low electric conductivity and because the linear electrodes are narrowed and elongated to realize larger-sized, higher-resolution screens. This causes a problem that, as a voltage pulse applied to an end of a linear electrode propagates toward the middle portion of the linear electrode, it is attenuated. To alleviate the problem, attempts have been to improve electric conductivity by partially laminating a thin metal electrode on the transparent electrode. However, this approach is limited in its ability to be applied to conventional flat display panels.
Moreover, in conventional flat display panels, two transparent insulation substrates are arranged so as to face each other and to define glow discharge spaces between them. Partition walls define the discharge space for each display cell. The display operation is performed by selectively controlling confront electrodes arranged in a matrix form. Hence, display cells cannot be independently controlled and, the thickness of the display panel structure becomes large, which are two serious problems.
Because of the limitations described above, a flat display panel with a novel structure different has been strongly desired. The present applicant proposed a flat display panel with a new structure in international application (PCT/JP98/01444) based on the Patent Cooperation Treaty. The flat display panel described in that publication includes a back substrate on which plural recessed portions each acting as a glow discharge space are arranged, and a transparent front substrate facing the back substrate and comprising areas (effective areas) respectively facing the recessed portions, each area having a pair of cell electrodes. In the flat display panel, pin electrodes penetrate the back plate so that a voltage signal can be applied to a given spot of an electrode formed on the front plate. That is, this structure allows a voltage to be applied between a pair of cell electrodes corresponding to a display cell so that the display cells can be respectively display-controlled by applying respective voltages. Because the back plate has recessed portions each for a discharge space, it is not necessary to form partition walls partitioning discharge spaces on the substrate, as were required in the previous art. Hence, this feature enables the manufacture of thinner display panels.
The basic structure of a flat display panel with the above-mentioned structure has been proposed. However, further improvement of the flat display structure is possible.
For example, in a typical conventional flat display panel, a metal electrode is laminated on a transparent electrode to reduce the resistance of the transparent electrode. Since this structure increases the unevenness of the surface on which electrodes are formed, the thin dielectric layer suitable to a low voltage drive operation tends to easily cause an electrical breakdown thereof. Thickening the dielectric layer in order to avoid such a problem results in an increase in the drive voltage.
To secure a stable glow discharge, the dielectric layer must be formed to have flat top surfaces. However, dielectric material which provides superior flatness is also prone to causing broken conductor because of the chemical reaction with the transparent electrode. For that reason, conventionally, a material with poor flatness but with low chemical reaction between the transparent electrode and the metal electrode is used. These problems remain in flat display panels with the above-mentioned new structure.
The present invention is made to solve the above-described problems in conventional flat display panels. It is an object of the present invention to provide a novel flat display panel that can decrease the drive voltage by suppressing the thickness of the dielectric film and can realize a stable glow discharge by suppressing deterioration of the cell electrode.
According to the present invention, the flat display panel comprises a back substrate in which plural recessed portions each acting as a discharge space are arranged; a transparent front substrate disposed so as to face the back substrate, and having effective regions respectively facing the recessed portions, and each including a pair of cell electrodes; pin electrodes penetrating the back substrate and erecting on the surface of the front substrate, each of the pin electrodes supplying a voltage to a cell electrode; and metal electrodes respectively disposed adjacent to the effective regions on the front substrate and respectively connected to the pin electrodes; wherein each of the cell electrodes is formed in a flat state using a transparent electrode layer, the cell electrodes extending near to the effective regions, the cell electrodes being respectively connected to the metal electrodes.
In a flat display panel according to the present invention, at least one of the pair of cell electrodes may be an individual electrode separated every display cell. The metal electrodes are respectively disposed to the individual electrodes, each of the metal electrodes having a pin electrode planted thereon.
According to the present invention, the flat display panel may further comprise a dielectric layer covering the transparent electrode layer, the dielectric layer having an opening at a portion where a pin electrode is planted on the metal electrode is planted, and edge portions of the dielectric layer defining the opening being positioned on the metal electrode.